Predictive drug testing on human tumor cells in order to define the appropriate chemotherapy will remain imperative as long as the anticancer agents available are few in number and show only limited activity. The advantages of an effective test would lie in obviating the need for testing antineoplastic agents on large cohorts of patients for assessment of drug activity (phase II studies) and in allowing determination of optimal use of anticancer agents (phase III trials). Such an in vitro test could help to better define dose and schedule of drugs preclinically. The additive value of...